The peanut butter may be contaminated with salmonella, bacteria that cause food poisoning.
Suspect jars bear a number on the lid beginning with the digits "2111." Any peanut butter carrying that number -- and bought since May 2006 -- should be discarded immediately.
All the peanut butter included in the warning was made at a ConAgra plant in Sylvester, Ga.
Since some Great Value brand peanut butter is not made by ConAgra, those jars are not affected by the warning.
Symptoms of salmonella food poisoning include fever, diarrhea, and abdominal cramps.
Salmonella can cause life-threatening infections in people in poor health or with weakened immune systems.
Call a doctor right away if you get any of the above symptoms after eating Peter Pan or Great Value brand peanut butter with the 2111 product code.
Doctors should report any illnesses to state or local health authorities.
The FDA warning is based on a CDC study linking 288 cases of food poisoning in 39 states to different types of Peter Pan peanut butter. The FDA says it learned of the study Feb. 13.
This salmonella outbreak is considered to be ongoing.
ConAgra will stop making food products at its Sylvester plant until FDA investigators determine the exact cause of the contamination.
"Although none of our extensive product tests have indicated the presence of salmonella, we are taking this precautionary measure because consumer health and safety is our top priority," ConAgra spokesman Chris Kircher says, in a news release.
"We are working closely with the FDA to better understand its concerns, and we will take whatever additional measures are needed to ensure the safety, quality, and wholesomeness of our products," Kircher notes.
The FDA will issue updates as more information becomes available.
Consumers who have questions should contact ConAgra's toll-free hotline at 866-344-6970.
SOURCES: News release, FDA. News release, ConAgra, ConAgra Foods Inc. web site.
By Daniel DeNoon
Reviewed by Michael Smith